make html tags and ModuleViews available in /docsrc/app.mjs

[jaeh]

at the moment, in src/cluster/build.mjs,
the app gets prepared before the modules get imported.

the modules then get imported in src/tasks/prepare/globals.mjs.

solution:
refactor the prepare steps to first get all html tags and all MagicModules,
then prepare the app, which in return will include /docsrc/app.mjs,
making modules work in the configuration of @magic-modules/gdpr and other components that have no representation in the code (@magic-modules/light-switch can also self-hoist once that functionality is added, being configured from app.mjs instead of being used in every page.)